Use of 4-amino pyridine for treatment of peripheral neuropathies

ABSTRACT

The present invention provides methods of using aminopyridine compounds to treat peripheral nervous system demyelinating diseases including Guillain-Barre Syndrome, diabetes mellitus, and hereditary sensory-motor neuropathies.

RELATED APPLICATION

This application claims priority of U.S. Provisional Patent ApplicationNo. 60/119,273 filed Feb. 9, 1999 which is incorporated herein byreference.

FIELD OF THE INVENTION

The subject invention relates to the treatment of peripheralneuropathies and, more specifically, to the treatment of demyelinatingperipheral neuropathies.

BACKGROUND OF THE INVENTION

By way of background, demyelinating neuropathies or diseases can occurin both the central nervous system and peripheral nervous system.Multiple sclerosis (MS) is a degenerative and inflammatory neurologicaldisease which affects the central nervous system and, more specifically,the myelin sheath. MS causes demyelination of nerve fibers which resultsin a short-circuiting of nerve impulses and thus a slowing or blockingof transmission along the nerve fibers with associated disablingsymptoms including spasticity, loss of motor strength, and painfuldysaesthesias (neurogenic pain). In contrast, with peripheraldemyelinating neuropathy, spasticity does not occur; however, weaknessand neurogenic pain are problematic. Peripheral neuropathies areassociated with a number of diseases, syndromes, or conditions includingbut not limited to acquired diseases or conditions includingGuillain-Barre Syndrome (GBS), chronic demyelinatingpolyradiculoneuropathy (CIDP), diabetic mellitus (prevalence of diabeticneuropathy alone is over one million in the United States), or thehereditary sensory-motor neuropathies (Charcopt-Marie-Tooth disease,Friedrich's ataxia, porphyria, lipoprotein neuropathies, and familialamyloid neuropathies).

U.S. Pat. No. 5,540,938 to Masterson et al., issued Jul. 30, 1996, andassigned to Elan Corporation discloses a method for the treatment ofneurological diseases characterized by central nervous systemdemyelination such as MS and Alzheimer's disease, by the administrationof mono- or di-aminopyridine to a patient having the central nervoussystem demyelinating disease. The Masterson et al. patent only teachesthe amelioration of symptoms associated with the central nervous systemdemyelating diseases and does not describe the use of aminopyridines forthe treatment of peripheral nervous system demyelating diseases or theirsymptoms.

U.S. Pat. No. 5,545,648 to Hansebout et al., issued Aug. 13, 1996, andassigned to the Canadian Spinal Research Organization, discloses the useof 4-aminopyridine for the reduction of chronic pain and spasticity inspinal cord injured patients. However, the Hansebout et al. patent onlydiscloses the use of 4-aminopyridine for the treatment of centralnervous system diseases and injuries such as spinal cord injury. (Seealso, Segal et al. (1998) “4-Aminopyridine Alters Gait Characteristicsand Enhances Locomotion in Spinal Cord Injured Humans,” The Journal ofSpinal Cord Medicine, Vol. 21, pp. 200-204.

It is interesting to note that, in general, central nervous systemdemyelinating diseases such as MS do not cross over to affect theperipheral nervous system as the peripheral myelin is different in bothits structure and response to antibodies than is, the central nervoussystem myelin even though both the peripheral myelin and central myelinprovide many of the same physiologic characteristics to the underlyingnerve. Furthermore, peripheral nervous system demyelinating diseasesusually spare the central nervous system as exemplified in GBS, diabetesmellitus, and hereditary sensory-motor neuropathies.

Accordingly, it would be advantageous and desirable to have a method fortreating peripheral nervous system demyelinating diseases. The use ofaminopyridines, specifically, 4-aminopyridine, shows promise inproviding a drug for use in the treatment of peripheral nervous systemdemyelinating diseases, such as GBS, which has previously not beenidentified in the prior art. The use of 4-aminopyridine for treatment ofperipheral nervous system demyelinating diseases fills a long-felt andpreviously unmet need by medical practitioners and those suffering fromperipheral nervous system demyelinating diseases for a treatmentmodality which can alleviate symptoms of their diseases.

SUMMARY OF THE INVENTION

According to the subject invention, there is disclosed a method fortreating a patient/subject having a peripheral nervous systemdemyelinating disease which includes the step of administering to apatient/subject having a peripheral nervous system demyelinating diseasea therapeutically effective amount of an aminopyridine compound.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages of the present invention will be readily appreciated asthe same becomes better understood by reference to the followingdetailed description when considered in connection with the accompanyingdrawings wherein:

FIG. 1 is a graph illustrating lower extremity motor strength over timefor both treated and untreated patients wherein the thin line representsthe placebo and the thick line represents the active drug;

FIG. 2 is a graph illustrating upper extremity motor strength over timefor untreated and treated patients wherein the thin line represents theplacebo and the thick line represents the active drug; and

FIG. 3 is a graph illustrating grip strength over time for untreated andtreated patients wherein the thin line represents the placebo and thethick line represents the active drug.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a method for treating a peripheralnervous system demyelinating disease by administering to a patient orsubject having a peripheral nervous system demyelinating disease atherapeutically amount of an aminopyridine, analogs, substituted forms,derivatives of aminopyridine, or the pharmaceutically acceptable salts,esters, amides, and prodrugs thereof.

The terms “patient” and “subject” mean all animals including humans.Examples of patients or subjects include humans, cows, dogs, cats,goats, sheep, and pigs.

The term “substituted” means that the base organic radical has one ormore substituents. For example, mono- or di-amino substituted pyridinesuch as 3,4-diaminopyridine.

Those skilled in the art are easily able to identify patients orsubjects having a peripheral nervous system demyelinating disease orcondition. For example, patients who are suffering from theGuillain-Barre syndrome (GBS) or diabetes mellitus.

A therapeutically effective amount is an amount of an aminopyridinecompound, that when administered to a patient or subject, ameliorates asymptom of the disease.

The compounds of the present invention can be administered to a patienteither alone or a part of a pharmaceutical composition. The compositionscan be administered to patients either orally, rectally, parenterally(intravenously, intramuscularly, or subcutaneously), intracisternally,intrathecally, intra-vaginally, intraperitoneally, intravesically,locally (powders, ointments, or drops), or as a buccal or nasal spray.

Compositions suitable for parenteral injection may comprisephysiologically acceptable sterile aqueous or nonaqueous solutions,dispersions, suspensions or emulsions, and sterile powders forreconstitution into sterile injectable solutions or dispersions.Examples of suitable aqueous and nonaqueous carriers, diluents, solventsor vehicles include water, ethanol, polyols (propyleneglycol,polyethyleneglycol, glycerol, and the like), suitable mixtures thereof,vegetable oils (such as olive oil) and injectable organic esters such asethyl oleate. Proper fluidity can be maintained, for example, by the useof a coating such as lecithin, by the maintenance of the requiredparticle size in the case of dispersions and by the use of surfactants.

These compositions may also contain adjuvants such as preserving,wetting, emulsifying, and dispensing agents. Prevention of the action ofmicroorganisms can be ensured by various antibacterial and antifungalagents, for example, parabens, chlorobutanol, phenol, sorbic acid, andthe like. It may also be desirable to include isotonic agents, forexample, sugars, sodium chloride, and the like. Prolonged absorption ofthe injectable pharmaceutical form can be brought about by the use ofagents delaying absorption, for example, aluminum monostearate andgelatin.

Solid dosage forms for oral administration include capsules, tablets,pills, powders, and granules. In such solid dosage forms, the activecompound is admixed with at least one inert customary excipient (orcarrier) such as sodium citrate or dicalcium phosphate or (a) fillers orextenders, as for example, starches, lactose, sucrose, glucose,mannitol, and silicic acid, (b) binders, as for example,carboxymethylcellulose, alignates, gelatin, polyvinylpyrrolidone,sucrose, and acacia, (c) humectants, as for example, glycerol, (d)disintegrating agents, as for example, agar-agar, calcium carbonate,potato or tapioca starch, alginic acid, certain complex silicates, andsodium carbonate, (e) solution retarders, as for example, paraffin, (f)absorption accelerators, as for example, quaternary ammonium compounds,(g) wetting agents, as for example, cetyl alcohol, and glycerolmonostearate, (h) adsorbents, as for example, kaolin and bentonite, and(i) lubricants, as for example, talc, calcium stearate, magnesiumstearate, solid polyethylene glycols, sodium lauryl sulfate, or mixturesthereof. In the case of capsules, tablets, and pills, the dosage formsmay also comprise buffering agents.

Solid compositions of a similar type may also be employed as fillers insoft and hard-filled gelatin capsules using such excipients as lactoseor milk sugar as well as high molecular weight polyethyleneglycols, andthe like.

Solid dosage forms such as tablets, dragees, capsules, pills, andgranules can be prepared with coatings and shells, such as entericcoatings and others well known in the art. They may contain opacifyingagents, and can also be of such composition that they release the activecompound or compounds in a certain part of the intestinal tract in adelayed manner. Examples of embedding compositions which can be used arepolymeric substances and waxes. The active compounds can also be inmicro-encapsulated form, if appropriate, with one or more of theabove-mentioned excipients.

Liquid dosage forms for oral administration include pharmaceuticallyacceptable emulsions, solutions, suspensions, syrups, and elixirs. Inaddition to the active compounds, the liquid dosage forms may containinert diluents commonly used in the art, such as water or othersolvents, solubilizing agents and emulsifiers, as for example, ethylalcohol, isopropyl alcohol, ethyl carbonate, ethyl acetate, benzylalcohol, benzyl alcohol, benzyl benzoate, propyleneglycol,1,3-butyleneglycol, dimethylformamide, oils, in particular, cottonseedoil, groundnut oil, corn germ oil, olive oil, castor oil and sesame oil,glycerol, tetrahydrofurfuryl alcohol, polyethyleneglycols and fatty acidesters of sorbitan or mixtures of these substances, and the like.

Besides such inert diluents, the composition can also include adjuvants,such as wetting agents, emulsifying and suspending agents, sweetening,flavoring, and perfuming agents.

Suspensions, in addition to the active compounds, may contain suspendingagents, as for example, ethoxylated isostearyl alcohols, polyoxyethylenesorbitol and sorbitan esters, microcrystalline cellulose, aluminummetahydroxide, bentonite, agar-agar and tragacanth, or mixtures of thesesubstances, and the like.

Compositions for rectal administrations are preferably suppositorieswhich can be prepared by mixing the compounds of the present inventionwith suitable non-irritating excipients or carriers such as cocoabutter, polyethyleneglycol or a suppository wax, which are solid atordinary temperatures but liquid at body temperature and therefore, meltin the rectum or vaginal cavity and release the active component.

Dosage forms for topical administration of a compound of this inventioninclude ointments, powders, sprays, and inhalants. The active componentis admixed under sterile conditions with a physiologically acceptablecarrier and any preservatives, buffers, or propellants as may berequired. Ophthalmic formulations, eye ointments, powders, and solutionare also contemplated as being within the scope of this invention.

The term “pharmaceutically acceptable salts, esters, amides, andprodrugs” as used herein refers to those carboxylate salts, amino acidaddition salts, esters, amides, and prodrugs of the compounds of thepresent invention which are, within the scope of sound medical judgment,suitable for use in contact with the tissues of patients without unduetoxicity, irritation, allergic response, and the like, commensurate witha reasonable benefit/risk ratio, and effective for their intended use,as well as the zwitterionic forms, where possible, of the compounds ofthe invention. The term “salts” refers to the relatively non-toxic,inorganic and organic acid addition salts of compounds of the presentinvention. These salts can be prepared in situ during the finalisolation and purification of the compounds or by separately reactingthe purified compound in its free base form with a suitable organic orinorganic acid and isolating the salt thus formed. Representative saltsinclude the hydrobromide, hydrochloride, sulfate, bisulfate, nitrate,acetate, oxalate, valerate, oleate, palmitate, stearate, laurate,borate, benzoate, lactate, phosphate, tosylate, citrate, maleate,fumarate, succinate, tartrate, naphthylate mesylate, glucoheptonate,lactobionate and laurylsulphonate salts, and the like. These may includecations based on the alkali and alkaline earth metals, such as sodium,lithium, potassium, calcium, magnesium, and the like, as well asnon-toxic ammonium, quaternary ammonium and amine cations including, butnot limited to ammonium, tetramethylammonium, tetraethylammonium,methylamine, dimethylamine, trimethylamine, triethylamine, ethylamine,and the like. (See, for example, S. M. Barge et al., “PharmaceuticalSalts,” J. Pharm. Sci., 1977, 66:1-19 which is incorporated herein byreference.).

Examples of pharmaceutically acceptable, non-toxic esters of thecompounds of this invention include C₁-C₆ alkyl esters wherein the alkylgroup is a straight or branched chain. Acceptable esters also includeC₅-C₇ cycloalkyl esters as well as arylalkyl esters such as, but notlimited to benzyl. C₁-C₄ alkyl esters are preferred. Esters of thecompounds of the present invention may be prepared according toconventional methods.

Examples of pharmaceutically acceptable, non-toxic amides of thecompounds of this invention include amides derived from ammonia, primaryC₁-C₆ alkyl amines and secondary C₁-C₆ dialkyl amines wherein the alkylgroups are straight or branched chain. In the case of secondary amines,the amine may also be in the form of a 5- or 6-membered heterocyclecontaining one nitrogen atom. Amides derived from ammonia, C₁-C₃ alkylprimary amines, and C₁-C₂ dialkyl secondary amines are preferred. Amidesof the compounds of the invention may be prepared according toconventional methods.

The term “prodrug” refers to compounds that are rapidly transformed invivo to yield the parent compounds of the above formula, for example, byhydrolysis in blood. A thorough discussion is provided in T. Higuchi andV. Stella, “Pro-drugs as Novel Delivery Systems,” Vol. 14 of the A.C.S.Symposium Series, and in Bioreversible Carriers in Drug Design, ed.Edward B. Roche, American Pharmaceutical Association and Pergamon Press,1987, both of which are incorporated herein by reference.

In addition, the compounds of the present invention can exist inunsolvated as well as solvated forms with pharmaceutically acceptablesolvents such as water, ethanol, and the like. In general, the solvatedforms are considered equivalent to the unsolvated forms for the purposesof the present invention.

The compounds of the present invention can be administered to a patientat dosage levels in the range of about 0.1 to about 1,000 mg per day.For a normal human adult having a body weight of about 70 kilograms, adosage in the range of about 0.01 to about 100 mg per kilogram of bodyweight per day is preferable. The specific dosage used, however, canvary. For example, the dosage can depend on a numbers of factorsincluding the requirements of the patient, the severity of the conditionbeing treated, and the pharmacological activity of the compound beingused. The determination of optimum dosages for a particular patient iswell known to those skilled in the art.

In addition, it is intended that the present invention cover compoundsmade either using standard organic synthetic techniques, includingcombinatorial chemistry or by biological methods, such as throughmetabolism.

The examples presented below are intended to illustrate particularembodiments of the invention and are not intended to limit the scope ofthe specification, including the claims, in any way.

Experimental Data

Study Design

This was a Phase I double-blind, placebo controlled, crossover, doseescalating study in subjects with GBS similar to those proposed for MSand SCI. An initial trial of ten patients will be randomized to none ofthe two treatment sequences (A or B) as shown below.

Population

The study population consists of subjects with GBS injury whoseneurological status has been stable for at least eighteen months. Tensubjects will be enrolled.

Inclusion Criteria

Male or female, 18 to 75 years of age, irrespective of race.

The subject is able to and has voluntarily given informed consent priorto the performance of any study specific procedures.

The subject has neurological impairment secondary to GBS which has beenstable for at least eighteen months.

The subject is unable to ambulate more than 200 feet without assistivedevices.

The subject is able and willing to comply with the protocol.

The subject has profound pain.

The subject has abnormal motor or sensory nerve conduction velocities inat least two tested nerves.

Exclusion Criteria

The subject is a pregnant female (as determined by a urine pregnancytest), a lactating female, or a female of child-bearing potential notusing one of the following methods of birth control (oral contraceptive,implantable conception device or injectable contraceptive agent, barriermethod of contraception) or not surgically sterilized.

The subject has a history of seizures.

The subject has a known allergy to pyridine-containing substances.

The subject has evidence of upper motor neuron involvement.

The subject has any medical condition, including psychiatric disease,which would interfere with the interpretation of the study monitor.

The subject has been on concomitant medications at a stable dose/regimenfor less than three weeks, and/or the stable dose/regimen of concomitantmedications is expected to be changed during the course of the study.

The subject has a history of drug or alcohol abuse within the past year.

The subject has received an investigational drug within thirty daysprior to the screening visit.

The subject has taken 4-aminopyridine in the past, whether throughparticipation in a previous study or self-medication.

Objective Neurological Functional Assessment

Variables to be Collected: The measures of neurological status reportedfor this study are:

Motor strength was rated on the traditional 0-5 ordinal scale:

0—absent motor strength

1—trace motor strength

2—can move the specified joint but only with gravity eliminated

3—can move the joint against gravity but not against any opposing force

4—can move the joint against opposing force but the strength is notnormal for the person or symmetrical

5—normal motor strength

This scale was employed to measure the following motor strength for eachof these joint motions on both the right and the left sides: hipflexion, hip adduction, hip abduction, knee flexion, knee extension,ankle dorsi-flexion, ankle plantar flexion, shoulder abduction, elbowextension, elbow flexion, wrist flexion, and wrist extension.

In addition, the following criteria were also rated:

Hand grip strength was measured on a hand dynamometer that had beencalibrated. Each patient was given three trials separated by thirtysecond rest periods and the strongest of the three measurements wasrecorded for each hand.

In addition, serum laboratories were drawn at the beginning of the studyand every week of the study. The serum laboratories included glucose,blood urea nitrogen, creatinine, uric acid, calcium, total protein,albumin, phosphate, total bilirubin, cholesterol, LDH, SGOT/AST,alkaline phosphatase, hematocrit, hemoglobin, red blood cell count,platelet count, and white blood cell count with differential.

Treatment variables to be collected include method of bladder managementas well as usage of a ventilator, plasmapheresis, steroids, andintravenous immunoglobulin (IVIg) as these variables are related to theseverity of disease (Zelig G, Ohry A, Shemsesh Y, Bar-On Z, Blumen M,Brooks M E. The rehabilitation of patients with severe Guillain-Barresyndrome. Paraplegia 1988; 26; 250-254; Meythaler J M, DeVivo M J,Braswell W C. Rehabilitation outcomes of patients who have developedGuillain-Barre Syndrome. Am J Phys Med Rehabil 1997; 76:411-419).Information will also be collected on GBS subtype, GBS etiology, generalpatient demographic characteristics, relevant medical history, length ofstay during acute care and rehabilitation, charges for acute care andrehabilitation, sponsors of care, and rehospitalizations (Meythaler J M.Rehabilitation of Guillain-Barre Syndrome. Arch Phys Med Rehabil 1997;78:872-9; Meythaler J M, DeVivo M J, Braswel W C. Rehabilitationoutcomes of patients who have developed Guillain-Barre syndrome. Am JPhys Med and Rehabil 1997; 76:411-9.). This data is part of thecurrently funded NIDRR study on GBS outcomes funded here at UAB.

Data Analysis/Database Development

The collectibility and ultimate quality of information contained in eachvariable is assessed both subjectively and objectively.

The entire project team reviews the reported frequency distributions,means, cross-tabulations, etc. of each variable for reasonableness. Forexample, if a high or low incidence of a particular complication isreported that seems inconsistent with the clinical experience of theinvestigators, then the definition of this variable will be reconsideredand either left unchanged, clarified or deleted as appropriate.Complications that do not occur in any cases will also be candidates fordeletion, while unanticipated occurrences may be candidates for additionto the database. This procedure has been used successfully by the ModelSpinal Cord Injury Systems for many years.

EMG NCS

All patients will have two upper and lower extremity motor and sensorynerve conditions (total four motor four sensory) performed at theenrollment period and at the maximal point of drug delivery in both theA and B phases. This assesses for objective improvement in nerveconduction velocity with the use of 4-AP. Nerve conduction velocitiesand amplitudes are performed for median and peroneal nerves.

Dosing Sequence

4-aminopyridine can be compounded. The drug was compounded locally by apharmaceutical compounding company (Scott Wepfer Rph, The CompoundingShoppe). This compound should be stable for a few weeks.

Sequence week 1 week 2 week 3 week 4 week 5 week 6 week 7 A 10 mg bid 15mg bid 20 mg bid washout placebo placebo placebo B placebo placeboplacebo washout 10 mg bid 15 mg bid 20 mg bid

The dose escalation only applies when the subject does not havedose-limiting toxicity.

Results

Eight patients were recruited for the double blind trial. There werethree males and five females. One female patient fell out of the studydue to the development of chronic demyelinating polyradiculoneuropathy(CIDP). This may have been partially masked by the 4-AP. The remainingseven patients, average age 57 (range 27-73), completed the double blindrandomized protocol.

Motor Strength

Lower extremity strength for hip abduction, hip adduction, hip flexion,knee flexion, ankle dorsiflexion and plantar flexion increased from anaverage motor score of 3.2 to 3.7 (p<0.0001, Friedeman's) on the activemedication as shown in FIG. 1.

Upper extremity strength for hip abduction, hip adduction, hip flexion,knee flexion, ankle dorsiflexion and plantar flexion increased from anaverage motor score of 3.2 to 3.7 (p=0.0065, Friedeman's) as shown inFIG. 2.

Grip strength also improved on the hand-held dynamometer. Grip strengthhad increased significantly from the start of the study as compared toafter four weeks of treatment (p=0.0243, paired Student's t-test). Overthe four week course the repeated measures ANOVA approached statisticalsignificance (p=0.0715, ANOVA) as shown in FIG. 3.

Labs

Only three laboratories had a statistically significant change. The uricacid changed from 6.4 to 6.5, the SGOT went up from 25.1 to 27.9, andthe hematocrit dropped from 42.7 to 41.6. None of these changes areclinically significant and may reflect statistical chance since so manylaboratories were tested. All other laboratories had no significantchange while on the active agent.

Placebo

There were no statistically significant finding while on the placeboagent. However, for those patients on the active agent first, the motorstrength and grip strength continued to drop for up to two additionalweeks after the one week washout period. This indicates the neuralbiological effects can last for more than two weeks.

In view of the teaching presented herein, other modifications andvariations of the present inventions will be readily apparent to thoseof skill in the art. The discussion, and description are illustrative ofsome embodiments of the present invention, but are not meant to belimitations on the practice thereof. It is the following claims,including all equivalents, which define the scope of the invention.

Any patents or publications mentioned in this specification areindicative of the levels of those skilled in the art to which theinvention pertains. These patents and publications are hereinincorporated by reference to the same extent as if each individualpublication was specifically and individually indicated to beincorporated by reference.

What is claimed:
 1. A method of treating a peripheral nervous systemdemyelinating disease, the method comprising administering to a patienthaving Guillain-Barre Syndrome a composition consisting essentially of atherapeutically effective amount of a mono-aminopyridine compound, orthe pharmaceutically acceptable salts, esters, amides and prodrugsthereof.
 2. A method according to claim 1, wherein themono-aminopyridine compound is 4-aminopyridine.
 3. A method according toclaim 1, wherein the peripheral demyelinating disease is Guillain-BarreSyndrome.
 4. A method of treating peripheral neuropathy, the methodcomprising administering to a patient having Guillain-Barre Syndrome atherapeutically effective amount of a mono-aminopyridine compound, orthe pharmaceutically acceptable salts, esters, amides and prodrugsthereof.
 5. A method according to claim 4, wherein themono-aminopyridine compound is 4-aminopyridine.